Air conditioners of the split or mini-split unit type for residential or office spaces have become extensively used. Such air conditioners have two separate units: a refrigerant fluid evaporation unit installed inside the room being cooled or heated (where heat is exchanged between the inside air and the refrigerant fluid), and a condenser unit located outside the air conditioned room (where heat is dissipated from the refrigerant fluid to the outside atmospheric air).
Heat is transferred to the outside air by inducing circulation of air through a finned coil by means of a fan. There are many designs and structures of these condensing units. A widely utilized design of the exterior condenser units comprises a cabinet with lateral walls open to the passage of ambient air through the enclosed finned heat-transfer coil, the compressor, and other components of the condenser unit of the air conditioning system, and a top air outlet through which a fan, having a horizontal plane of rotation located at the upper part of said cabinet, forces a generally upward flow of air from across the lateral walls.
Usually the motor of the fan is located centrally in respect to a circular outlet at the upper cover of the cabinet. The fan motor normally is secured to the cabinet by means of a plurality of supporting elements.
The air outlet is protected by a cover, which permits the passage of air while obstructing fingers and most objects of that size and larger from passing in to reach the fan blades. This fan guard may be made for example of steel sheet with perforations or of steel wire formed in spaced-apart concentric circles or in a spaced-apart spiral winding in cooperation with radial supporting elements. The design and structure of this fan guard must comply with the safety standards; yet it must offer a minimum resistance to the air flow in order to increase the heat-transfer efficiency and have less energy consumption by the driving motor.
The fan guards made of steel wire that are normally utilized may have a central plate made of steel sheet (dish) which provides mechanical strength to the guard and rarely may provide a solid base for fastening the fan motor by means of screws or any other suitable fasteners
There is an unsatisfied need in the air conditioning units market for a fan guard of low cost, which also has the suitable mechanical strength for better supporting weight and rotational forces of the fan motor and which meets the safety norms regarding the spacing of the elements forming the guard and also offers a low resistance to air flow across said guard in order to decrease the capacity and energy consumption of said motor.
U.S. Pat. No. 3,865,517 to Simmonds et al describes an air conditioning split apparatus wherein the outside unit has an upper air outlet and a guard covering said outlet for protecting the motor and the fan. The guard is formed by concentric rings fastened to a plurality of radial elements in a manner not disclosed by this patent, since the drawings show a gap between the radial elements and the rings constituting the guard. The fan motor is supported by said radial elements that bend towards the inner part of the air conditioning apparatus supporting said fan motor at the sides part of its housing. Though this patent mentions that the central plate 29 is used for esthetic purposes and for protection of the motor, it is inferred that said plate also cooperates significantly to increase the mechanical strength of the guard because the radial elements 15 pass through said plate thus forming a unitary structure.
U.S. Pat. No. 6,866,474 to Aubuchon describes an impervious protective cover (preferably of a heavy vinyl cloth) to be used on the upper part of an air conditioner condenser unit when not in use for an extended time period, which cover is shaped to extend downwardly to at least the plane of rotation of the horizontal fan blades, but preferably not more than half way (so as to accumulation of most debris while not trapping excess moisture). The fan motor 46 is incidentally shown to be mounted on the underside of a central plate 29 of the top outlet grill.
U.S. Pat. No. 6,866,474 to Uselton shows a fan guard 40 for an air conditioning system having a top air outlet 38 and a fan guard 40. This patent clearly shows in FIGS. 1 and 3 that the motor 32 and fan 26 are secured well below and entirely apart from the fan guard 40 by means of laterally projecting supporting members 34. As shown in FIG. 3, the guard design comprises a plurality of radial elements 44, 46 a plurality of circular or spiral elements 50, 32 and a central disk shaped hub 42, but this guard is not intended for supporting the fan motor.
U.S. Pat. No. 8,191,381 to Kim et al. discloses an outdoor fan for an air-conditioning unit with some characteristics that allow for a reduced energy-consumption and reduced noise during its operation. FIG. 2 shows a fan guard made of what appears to be concentric wire elements but the fan motor (10, 110) being positioned below the fan (40, 140) as indicated in FIG. 1 clearly would not be in a position to be supported by the fan guard (there being no illustration nor description of how the fan motor is supported).
No fan guard incorporating all the features and advantages of the invention was found in the prior art.